How to Retrofit Vapour Control Without the Mess

Retrofitting Vapour Control: What If It Was Missed?

Don’t Panic - There’s Still a Solution!

Vapour control is a critical part of any airtight, energy-efficient building. It helps prevent moisture from entering insulation layers, protects the building fabric, and supports high-performance standards such as Passivhaus.

But what happens if you realise after construction or renovation that vapour control wasn’t included?

Fortunately, it’s not too late. With liquid-applied airtight membranes from Intelligent Membranes, vapour control can be added during retrofit without major disruption to the building.

Can Vapour Control Be Added After Construction?

Yes. Traditional vapour control membranes often require walls to be opened up, finishes removed, and significant rework to install properly. This can lead to delays, additional costs, and unnecessary mess.

Liquid-applied systems provide a far simpler solution.

Passive Purple, our Passivhaus-certified airtight membrane, can be applied directly to internal surfaces to create a continuous vapour control and airtight layer.

Application Options

Already plastered walls

If the wall is already plastered and finished, Airtight White can be applied directly to the surface. This provides both airtightness and vapour control without the need to remove existing finishes.

Decorative flexibility

Airtight White can also be painted over with standard decorative paints, allowing you to maintain your chosen interior design while still achieving the required performance.

Why Liquid-Applied Vapour Control Is So Effective

Traditional sheet membranes and tapes can struggle around corners, service penetrations, and irregular surfaces. Even small gaps can compromise performance.

Liquid-applied membranes behave differently. They flow into joints, cracks, and complex junctions to form a continuous, seamless air and vapour control layer.

This approach delivers several advantages:

• Complete coverage across uneven or complex surfaces

• Improved airtightness test performance

• Reduced risk of moisture entering insulation layers

• Long-term protection of the building structure

• Compatibility with Passivhaus retrofit and low-energy building standards

Retrofit Vapour Control Without Major Disruption

If vapour control was missed during the original build, it doesn’t have to mean starting again. Using Passive Purple, Airtight White, and Supergrip, vapour control can be added quickly and effectively as part of a retrofit solution.

These systems allow contractors and homeowners to correct issues without removing large sections of the building fabric, saving time, labour, and cost.

Missing vapour control doesn’t have to be a disaster. With the right liquid-applied solutions, it can be retrofitted easily while improving airtightness, moisture management, and overall building performance.

📞 Contact the Intelligent Membranes team to find out how our liquid-applied airtight systems can help retrofit vapour control into your project.